1. Field of the Invention
The present invention relates to the preparation of polychloroprene by polymerization of chloroprene in the presence of certain additives, as well as to the resulting polychloroprene itself, and mixtures of a vulcanizable rubber and a sol of a polychloroprene thus prepared.
2. Description of the Prior Art
It is known to this art to conduct the polymerization of chloroprene in the presence of a chain-transfer agent (for the control of molecular weight), such as a mercaptan or a xanthogen disulfide, optionally in combination with a minor amount of elemental sulfur. Polymerization in the presence of an alkylxanthogen disulfide results in the production of polychloroprenes, which, relative to the same polymers produced in the presence of mercaptans, have high mechanical properties, in particular tensile strength, but which are affected upon aging. Furthermore, polymers modified by a xanthogen disulfide present the disadvantage of premature vulcanization during downstream conversion stages, such as the molding of compositions containing same, resulting in undesirable scorching.